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 Post subject: Non-rebounding Perazzi hammers
PostPosted: Sun Aug 09, 2009 5:16 pm 
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Location: Dallas, Texas
I have an MX-8B with the removable coil spring triggers. Over time the gun has become more and more difficult to open. Looking at it closely I observed that the firing pins are projecting after firing and hanging up on the primer indent pockets. In looking at the trigger it appears that the hammers are not rebounding, when I put my flat spring trigger from my other Perazzi in the gun, the hammers rebound and the firing pins do not protrude. As I look at the coil spring trigger it appears fine and I cannot see how the hammers are supposed to rebound. Have you all seen this before? Are the coil spring triggers supposed to rebound? Any solutions other than shipping it off to Giacomo?

Thanks,
rickdm


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Sun Aug 09, 2009 6:52 pm 
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I believe what you are seeing is normal and correct.

Is the coil spring trigger correct for the gun that is us being used in ?

I have seen coil spring guns with a notch out of the monobloc in the centre of the bottom barrel chamber to clear the firing pin that hangs forward due to the coil springs.

Are you sure it is the primers indent that the pin is hanging up on ??

Bryce


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Sun Aug 09, 2009 7:23 pm 
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Bryce, what leads me to believe it is the primer is that I can see a scrape in the primer metal after forcing the gun open. It is the original trigger for that gun, and when I use the flat spring trigger from my other gun, it opens with little resistance.

rickdm


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Sun Aug 09, 2009 8:00 pm 
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Rick,

Does the gun have the notch out of the bottom of the bottom barrel chamber right at the back of the monobloc ? If not is there any sign of contact in that area.

I wonder if perhaps the pins have accumulated a bit of crud or primer scrapings and are actually hanging more forward than the hammers would usually dictate. If they are they hang up in the primers worse and worse collecting more shaving and getting worse still. If it really hung up badly it may even be possible to have bent the bottom barrel firing pin, although they would seem to be pretty tough ??

I'd take the pins out, check them over and clean out the holes, maybe even just replace them for insurance. They are easy to get out, just push the retaining pin to the side and they come free, little springs behind each. Push the retaining pin from left and out to the right and just push it far enough to let the far pin come free, that pin serves as a pivot for the top lever realease mechanism and pushing it to far out will result in that coming apart also.

Bryce


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Sun Aug 09, 2009 11:10 pm 
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This is all new to me. I wasn't aware that the hammers were supposed to 'rebound'. Is this so the firing pin has room to move back? The hammer in my trigger group doesn't seem to have any provision for this. Why would one trigger group work fine and one cause issues?

Aren't modern firing pins made to be 'inertial' so that they don't protrude even though the hammer is dropped? Inertial firing pins are common in hand guns. This way you can have a round in the chamber and the hammer down and no chance of the round going off. However, when the hammer hits with normal force, after being released from the cocked position, the inertia of the firing pin drives it into the primer. Then the firing pin return spring keeps it back from the next round until the process happens all over again. I only mention this because protruding firing pins are usually caused by dirt build up in the receiver. Perazzis may be different and I wish to learn so, I'm asking....

Also if the firing pin were dragging on the primer wouldn't it drag on the hull base as well? Do you see any marks on the brass?

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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 1:19 pm 
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Bryce. wrote:
I believe what you are seeing is normal and correct.


x2. Coil spring hammers do not rebound where as flat spring hammers do. Actually, with a flat spring, firing the gun actually drives the spring a bit past its normal resting point and it then relaxes to its normal position which withdraws the hammer.

When is the gun hard to open? Is the top lever hard to move or is it hard to get the barrels starting to move? If it's the first, put a tiny dab of grease on top of each of the locking lugs per the instructions in the manual and this will make the top lever much easier to move.

If it's hard to get the gun to start to open, cock the hammers, pull the stock, drift out the firing pin retaining pin, remove the pins, and carefully clean the firing pin channels. Make sure the firing pin springs come out of the channels. Sometimes they can get wedged in with some of the crud. Be very careful not to mix up the top and bottom pins. They are different lengths and if you put the long pin in where the short pin is supposed to go and fire a shell, you won't easily get the gun open again. I wouldn't be surprised if there were a build up of crud in the firing pin channel which is preventing the pins (especially the bottom pin) from withdrawing quickly/completely which, on an MX-12, happens as the gun is cocked when it is opened.


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 7:02 pm 
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Location: Dallas, Texas
I will remove the firing pins to see if there is any binding, though I can reach into the receiver and move the firing pins back and forth and I do not feel any grit or binding. The top lever moves to the right easily, it is the opening of the gun that is difficult. I cleaned out the trigger group this weekend and so even with no crud on the hammer the lower firing pin is still protruding. As I look at this design I cannot figure out how the firing pins ever retracted.

rickdm


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 7:54 pm 
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Rick,

With the coil springs the pins will protrude a little.

I wonder if there is some issue with pin length, just how far do they poke out from the breach face ?

Are the pins original for the gun.

There are new and old pins and new and old style hammers, have either ever been changed ?? The old style right hand hammer has a cut of the front of the hammer face that doesn't go all the way across, the newer ones that same cut goes all the way across side to side. The later style pins will be hit by the edge of the uncut area on an older style hammer.

I guess a new pin in an older hammer style coil spring trigger gun could result in the side of the bottom barrel hammer holding the pin further forward than it should rest at ???

Bryce


Last edited by Bryce. on Mon Aug 10, 2009 8:34 pm, edited 4 times in total.

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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 8:29 pm 
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Rastoff,

In a leaf spring MX8 trigger the geometry of the hammer, bridle and spring is such that when the hammer is uncocked and forward the spring pulling up on the bridle which in turn pulls on the hammer actually dictates the "at rest" position of the hammer. The spring is still under tension when the hammer is forward but it is the geometry that positions the hammer not a physical stopper that the hammer rests on. With the trigger out of the gun you can pull the hammer further forward past its resting point.

When the gun is fired the hammer reaches that geometry dictated "at rest" position and it's own inertia actually carries it past that spot forwards until it hits the breech face and the firing pins. In this case the pins do not travel full depth on hammer force but instead continue on under their own inertia also. The hammer, bridle and spring geometry then once again take control of the hammer and the fired but now resting hammer sits back away from the breech face and the firing pins.

If a coil spring trigger group had a fired hammer position the same as the leaf spring trigger does the hammer would need a physical stop to rest on and that position would not allow the hammer to reach the pin at all. The coil spring pushes axially onto the hammer and there is no way to have the same geometry that creates the hammer position as in the leaf spring trigger.

The result is that the fired hammer position for the coil spring is the same as the forward most position of the leaf spring. The difference being that the coil spring hammer stays there and the leaf spring powered hammer moves back again due to that geometry mentioned earlier. If you had an uncocked trigger of both types in hand the hammers of the coil one would be sitting further forward by about 1/4 inch or so.

What that means is for any given MX8 type action a leaf spring (my preference) trigger will leave the firing pins retracted fully after firing and a coil spring trigger will leave the hammers resting on the back of the pins making them protrude from the action face. The pins are not held fully forward at maximum protrusion but they do still stick out from the breech face.

I don't know if this is usually a problem or not to be honest but whatever problem it does create stems from the fact that it would seem impractical to make firing pins and triggers that work together ie a certain set of pins that work with a certain trigger and a different type of pin that works with the other type of trigger. The logic I guess is that a gun must be usable with either trigger type or it negates some of the purpose of the drop out design.

I believe your single barrel gun has a coil spring set up, perhaps there isn't the same compatibility issues needing both spring types to work, is there such a thing as a leaf spring version of your trigger ???

Bryce


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 9:20 pm 
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Thanks for the explanation Bryce. I took out the triggers from my DT10 and TMS. One is coil and the other is leaf spring.
Image

Here's the DT10. I checked the 'play' in the hammers and here is what I found:
Image
Notice that the top hammer is back a little further than the bottom hammer. This shows the amount of play left after the hammer has been released. This is a good indication of the inertial aspect of the leaf design. Interesting...I never knew that. My coil spring hammer from the TMS has no play due to the pressure constantly exerted from the spring.

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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 9:37 pm 
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That is the ticket Rastoff.

On a Perazzi trigger the hammers will not actually sit there like you show with the one hammer forward on the DT10 trigger. You can pull them forward but the spring will pull them back to their rested position.

I don't know if the DT10 does or not but the Perazzi uses a bridle on the hammer, essentially a pivoting attachment that is fixed to the hammer that the little hooked end of the spring pulls up on.

You can see the bridle sticking up with the top leaf of the spring hooked under it. Imagine a bridle as in horse riding stuff, shape is along those lines, basically a sort of plat sided looped link between hammer and spring. If you take the spring out the bridle is free to flop back and forth but constrained sideways. You lever the spring in with the tool and flip the bridle over the hooked end on the spring and the spring tension holds it all where it ought to be.

Bryce

Image


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 9:50 pm 
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Yes, I get it. The Beretta is essentially the same, but the hammers are not constrained/held/assisted by the 'bridal' you describe. Also the springs are in a completely different geometry. Still, the end result is the same.

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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 10:06 pm 
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That it is.

I don't want to sound like a Perazzi fan boy but what I could never figure with the DT10 was the trigger comes out and it uses a leaf spring but you can get at the spring to replace it readily. Unless you have a spare trigger the drop out business isn't used to it's full potential. With the Perazzi spring being right at the top of the trigger readily accessed you just need springs and the simple tool to replace a broken spring making a second trigger group a luxury rather than a necessity to get any drop out benefits.

Perhaps the big beefy DT10 springs simply don't break ??

Bryce


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Mon Aug 10, 2009 11:44 pm 
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Well, the Perazzi may be easier to change. I don't know as I've never changed either. But, the DT10 springs can be replaced by pushing out a couple of pins. Still a 10 minute or less job if you know what you're doing. That's just an assumption on my part because I've never done it. Just looking at it tells me that it's not all that hard if necessary.

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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Tue Aug 11, 2009 5:23 pm 
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Bryce, the firing pins and hammers are the factory originals. The top firing pin protrudes only slightly, the bottom pin portrudes all the way. I will check on the notches when I get home from work.

A side question. I also have a couple of Perazzi flat spring triggers with Allem releases. Does the release mechanism block you from removing the flat springs should you have a problem?

Thanks,
rickdm


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Tue Aug 11, 2009 5:51 pm 
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Rick,

I'd have a careful look at the pins and the hammers, look for impact marks on the hammer that are on the edge of the cut if the bottom barrel hammer cut does not go all the way across the hammer face. It is the recessed area that hits the pin that I am talking about. If the pin were bent or of the wrong type somehow that could make it hang forward.

I don't recall seeing a pin hanging all the way forward, only a little, I think something is not right.

I'd definitely pull out the firing pins and check them over.

If you posted some pictures it might help identify an issue, hammer faces especially.

That isn't my Allems in the picture, I don't use one. I do believe I read however that with the Allems set up you can remove the springs but the tool needs to be modified to work around the release hooks. I don't know that for a fact, it should become pretty apparent if you have a trigger with the hooks and a normal Perazzi spring removal tool.

Bryce


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Thu Aug 13, 2009 7:42 pm 
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Sorry it has taken me this long to figure out how to post pictures to the forum. Here are two pictures, the first one shows the projecting lower firing pin, and the second one shows a comparison between a coil spring trigger on the bottom and the flat spring on the top. You can see how much further forward the coil spring hammer rests.

Image
Image

I checked the notches and alignment for the hammer and firing pins and they seem to be fine.

BTW, the problem with removing flat springs from a release trigger is not the tool, but once you unhook the springs there appears to be no way to get them out without removing the release trigger hooks.

rickdm


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Thu Aug 13, 2009 11:23 pm 
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Rick,

As best I can tell everything looks right but I don't know precisely how far the pins should protrude.

I wonder if it is possible for the pins to be mixed up so that they still function but not as intended ? Each pin is position specific but I have never tried them in the wrong spot to know what difference it would make.

Is there a chance of some wear on the pins ? Again I don't know how that would create this problem but failing all else.

I'd certainly be pulling them out and comparing them to a fresh new set, and cleaning the pin holes throughly while in there.

Worst case scenario you could use a leaf spring trigger in that gun to get the pins further back !

There has to be some problem some place if it hasn't always done that, I struggle to understand how the gun is simply intended to be that way.

Good luck.

Bryce


PS That is what I wondered about the release as well. The only way it seemed possible to remove the springs with the hooks in place would be to rotate them backwards on the locating pin but I don't know if that would actually get them free of the hooks or not.


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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Thu Aug 13, 2009 11:41 pm 
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Bryce I think you've hit on it. I just pulled out my spare firing pins for my DT10 and one is noticeably longer than the other. Is it possible to get them in the wrong position? That would certainly explain the problem rickdm is having.

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 Post subject: Re: Non-rebounding Perazzi hammers
PostPosted: Fri Aug 14, 2009 6:11 am 
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Bryce. wrote:
I wonder if it is possible for the pins to be mixed up so that they still function but not as intended ? Each pin is position specific but I have never tried them in the wrong spot to know what difference it would make.


i mentioned this in my post above. If the pins get switched so that the longer pin is in the place where the shorter pin should go, the gun will be basically impossible to open. As I understand, the pin in the wrong position will protrude out enough so that it basically has to be broken off to let the gun open.

EDIT: Or you take the gun apart and pull the pins out to get it open.


Last edited by bopper on Fri Aug 14, 2009 8:34 am, edited 1 time in total.

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